Amazon sailfin catfish found in Sindh waters, experts warn of invasive spread

Foreign aquarium species reaches Karachi Fish Harbour, threatening aquatic biodiversity

KARACHI:

An unusual fish brought from a dhund, or shallow pond, near Sukkur to the Karachi Fish Harbour on January 4, 2026, has been identified as an Amazon sailfin catfish, officials and experts said.

The foreign species, which is not native to Pakistan, is believed to have accidentally entered natural water bodies and has now spread across Sindh and parts of lower Punjab. The fish initially went unidentified and was described by handlers as an alien species.

The Amazon sailfin catfish is characterised by a body covered with bony plates and a thick, armoured structure. Native to Latin America, it is popular around the world as an aquarium fish but is also known as a highly successful invasive species.

Experts say the fish has now spread on such a large scale in Pakistan that its eradication or effective control is no longer possible.

The species is among at least 26 fish introduced into Pakistan either deliberately or accidentally that later became invasive. These species are having harmful effects on the country’s aquatic biodiversity and are disrupting the balance and functioning of natural ecosystems.

Pakistan’s first alien fish species, brown trout and rainbow trout, were introduced in 1928 in parts of what is now Khyber Pakhtunkhwa. Over time, several other non-native species were brought in to boost fish production or control aquatic weeds, including Mozambique tilapia, common carp, goldfish and grass carp.

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In the 1980s, silver carp, bighead carp, Nile tilapia and blue tilapia were also introduced. Grass carp was later reintroduced to further enhance aquaculture production. All of these species have since established themselves in Pakistan’s natural water bodies, affecting native plants and animals.

Experts say the main goal behind introducing these species was to increase aquaculture output, while their long-term environmental impact was largely overlooked.

According to WWF Pakistan, there is no disagreement that the introduction of alien fish species has adversely affected aquatic biodiversity and natural ecosystems across the country.